WARNING: This article contains major spoilers for "The Missing Link," the penultimate episode of Supergirl Season 5.
Supergirl's Alex Danvers is about to become a vigilante in her own right.
In "The Missing Link," the penultimate episode of Season 5, Kara and Alex met up with Kelly's friend Pete (Sean Astin), who offered to help them track a Leviathan symbol. Midway through their research, Kara was called away, leaving Alex and Pete to fend for themselves. As they attempted to uncover Leviathan's current location, they came under fire from the organization's agents. They managed to escape, but without the information they sought.
When Alex returned home, Kelly asked how her mission with Pete went. "We were ambushed by Leviathan," Alex admitted. "Pete is okay. It's fine. I just -- look, I made a mistake. I pressed and I put him in danger. I'm not used to being so exposed and now with the DEO, it's gone."
"I'm so sorry," Kelly said. "Oh, and speaking of exposed, William and I discovered that Eve Teschmacher has been working for Obsidian."
"Have you talked to Andrea?" Alex asked, to which Kelly replied, "She didn't care. In this world, there is no record of Eve being anything but perfect. She threatened to fire me if I came to her again."
"So what are you going to do? Are you going to leave Obsidian?" Alex pressed.
"No!" Kelly shot back. "No, that'll make it so much harder to get to the bottom of this. I've got to get better at hiding." She paused, a new idea coming to her. "Maybe you should too."
"What do you mean? Like, wear a mask?" Alex joked.
"It worked for my brother," Kelly replied, completely serious. "If you're going to be a vigilante, you might as well go all the way."
Up until "Crisis on Infinite Earths," Alex had worked for the Department of Extranormal Operations (DEO). However, when Lex rewrote reality to become head of the DEO, Alex quit. Ever since, she has felt adrift. This -- and her father's death -- eventually drove her into Obsidian's virtual reality, where she masqueraded as Supergirl. Although it eventually went terribly wrong, the experience helped her develop a taste for helping others as a vigilante as opposed to a government agent. Between this and Kelly's suggestion, it shouldn't be a surprise if Alex adopts her own vigilante persona soon.
Airing Sundays at 9 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter and Chyler Leigh as Alex Danvers. The Season 5 finale will air May 17.